Si3461 SINGLE-PORT IEEE 802.3AT POE/POE+ PSE INTERFACE Features Pin Assignments CLSMARK 1 STATUS ISENSE 8 RST 4 7 VSENSE 5 6 DETA 3 DC2 CLSMODE GND 11 VDD 3x3 mm PCB footprint; RoHS-compliant 3-point detection algorithm eliminates false detection events 10 9 DC1 2 Tiny Robust 11 11 Si3461 11 IEEE-compliant disconnect IEEE 802.3atTM compliant PSE Inrush current control Autonomous operation requires Short-circuit output fault no host processor interface protection Complete reference design LED status signal (detect, power good, output fault) available, including Si3461 controller and schematic: UNH Interoperability Test Lab report available Low-cost BOM Compact PCB footprint Extended operating range Operates directly from a +50 V (–40 to +85 °C) isolated supply 11-Pin Quad Flat No-Lead Supports up to 30 W maximum (QFN) package output power (Class 4) 11-pin QFN (3x3 mm) Top View—Pads on bottom of package Applications IEEE 802.3at endpoints and midspans Environment A and B PSEs Embedded PSEs Set-top boxes FTTH media converters Cable modem and DSL gateways Description The Si3461 is a single-port power management controller for IEEE 802.3at-compliant Power Sourcing Equipment (PSE). The Si3461 can be powered from a 50 V input using a shunt regulator, or, to save power, it can be powered from 50 V and 3.3 V power supplies. The IEEE-required Powered Device (PD) detection feature uses a robust 3-point algorithm to avoid false detection events. The Si3461's reference design kit also provides full IEEE-compliant classification and PD disconnect. Intelligent protection circuitry includes input undervoltage lockout (UVLO), classification-based current limiting, and output short-circuit protection. The Si3461 is designed to operate completely independently of host processor control. An LED status signal is provided to indicate the port status, including detection, power good, and output fault event information. The Si3461 is pinprogrammable to support four available power levels, endpoint and mid-span applications, and auto-retry or restart after disconnect functions. A comprehensive reference design kit is available (Si3461EVB), including a complete schematic and bill of materials. Rev. 1.0 5/10 Copyright © 2010 by Silicon Laboratories Si3461 Si3461 2 Rev. 1.0 Si3461 TABLE O F C ONTENTS Section Page 1. Typical Application Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 2. Si3461 Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 2.1. Si3461-EVB Performance Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 2.2. PSE Timing Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 3. Typical Si3461-EVB Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4. Si3461-EVB Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 4.1. Reset State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12 4.2. Operating Mode Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 5. Operating Mode Sequencing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 5.1. Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 5.2. Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 5.3. Power-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 5.4. Overload Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 5.5. Disconnect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 5.6. UVLO and OVLO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 5.7. Status LED Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14 6. Design Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 6.1. Isolation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 6.2. External Component Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 6.3. Input DC Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 7. Si3461 Pin Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 8. Ordering Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 9. Package Outline: 11-Pin QFN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 9.1. Solder Paste Mask . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 9.2. PCB Landing Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 9.3. Marking Specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Document Change List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23 Contact Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24 Rev. 1.0 3 Si3461 1. Typical Application Schematic VIN +50V +50V + Optional 3.3V regulator VDD +3.3V Detect & Mark VDD Si3461 GND GND Classification & Gate drive DETA VSENSE ISENSE STATUS RST GND CLSMARK DC1 DC2 CLSMODE PSE output (to port magnetics) DETECT FAULT PGOOD - Note: Refer to the Si3461-EVB User Guide for complete schematic details Figure 1. Si3461 Typical Application Schematic 4 VOUT 48 V Rev. 1.0 Si3461 2. Si3461 Electrical Specifications The following specifications apply to the Si3461 controller. Refer to Tables 4 and 5 and the Si3461-EVB User's Guide and schematics for additional details about the electrical specifications of the Si3461-EVB reference design. Table 1. Recommended Operating Conditions Description Symbol Test Conditions Min Typ Max Unit –40 25 +85 °C Operating Temperature Range TA Thermal Impedance JA No airflow — 75 — °C/W VDD During all operating modes (detect, classification, disconnect) 2.7 3.3 3.6 V VDD Input Supply Voltage Table 2. Absolute Maximum Ratings* Conditions Max Rating Unit Ambient Temperature Under Bias –55 to +125 °C Storage Temperature –65 to +150 °C –0.3 to 5.8 V Voltage on VDD with respect to GND –0.3 to 4.2 V Maximum Total Current through VDD and GND 500 mA Maximum Output Current into CLSMARK, DC1, DC2, CLSMODE, STATUS, ISENSE, RST, VSENSE, DETA (any I/O pin) 100 mA Human Body Model –2 kV to +2 kV V Soldering, 10 seconds maximum 260 °C Parameter VDD > 2.2 V Voltage on RST or any I/O pin with respect to GND ESD Tolerance Lead Temperature *Note: Stresses above those listed in this table may cause permanent device damage. This is a stress rating only, and functional operation of the devices at these or any conditions above those indicated in the operational listings of this specification is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability. Rev. 1.0 5 Si3461 Table 3. Electrical Characteristics* Description Symbol Test Conditions Min Typ Max Unit Digital Pins: CLSMARK, DC1, DC2, CLSMODE, STATUS (Output mode), RST Output High Voltage VOH IOH = –3 mA IOH = –10 µA 0.7 x VDD VDD – 0.1 — — — — V Output Low Voltage VOL IOL = 8.5 mA IOL = 10 µA — — — — 0.6 0.1 V Input High Voltage VIH Any digital pin 0.7 x VDD Input Low Voltage VIL Any digital pin — — 0.6 V Input Leakage Current IIL VIN = 0 V — ±1 — µA — 5 — pF — ±1 — µA V Analog Pins: ISENSE, VSENSE, DETA, STATUS (Input mode) Input Capacitance Input Leakage Current IIL *Note: VDD = 2.7 to 3.6 V, –40 to +85 °C unless otherwise specified. 6 Rev. 1.0 Si3461 2.1. Si3461-EVB Performance Characteristics When implemented according to the recommended external component and layout guidelines for the Si3461-EVB, the Si3461 enables the following performance specifications in single-port PSE applications. Refer to the Si3461EVB User's Guide and schematics for details. Table 4. Selected Electrical Specifications (Si3461-EVB) Symbol Test Conditions Min Typ1 Max Unit VIN Input Supply Range VIN –40 to +85 °C ambient range 45 50 57 V VIN Input UVLO Voltage UVLO UVLO turn-off voltage at VIN — 45 V VIN Input OVLO Voltage OVLO OVLO turn-off voltage at VIN 57 60 — V VDD Supply Voltage Range VDD Si3461 supply voltage range 3.15 3.3 3.45 V Output Supply Voltage VOUT PSE output voltage at VIN = 50 V and IOUT = 350 mA — 49 — V Supply Current IIN Current into the VDD node (not including shunt regulator) — 8.0 10.5 mA Detection Voltage VDET Detection point 1 Detection point 2 Detection point 3 — 4.0 8.0 4.0 — V Detection Current IDET Short circuit — — 3 mA Description Power Supplies 42 Detection Specifications Minimum Signature Resistance RDETmin 15 17 19 k Maximum Signature Resistance RDETmax 26.5 29 33 k Classification Specifications Classification Voltage VCLASS 0 mA < ICLASS < 45 mA 15.5 — 20.5 V Classification Current Limit ICLASS Measured with 100 across VOUT 55 75 95 mA Notes: 1. Typical specifications are based on an ambient operating temperature of 25 °C and VIN = +50 V unless otherwise specified. 2. Absolute classification current limits are configurable. See “5.2. Classification” and "5.3. Power-Up" on page 13. 3. Typical ICUT values are adjusted according to the input voltage to provide power limiting with approximately 5% margin against the 802.3 requirements. The maximum ICUT values are consistent with the IEEE requirement that Icut maximum is less than 400 mA at the minimum allowed Vout of 44 V or 684 mA for PoE+ mode at the minimum allowed Vout of 50 V. 4. Overload current is within limits, typically in less than 1 ms. Rev. 1.0 7 Si3461 Table 4. Selected Electrical Specifications (Si3461-EVB) (Continued) Description Classification Current Region Symbol Test Conditions Min Typ1 Max Unit ICLASS_REGION Class 0 0 — 5 mA Class 1 8 — 13 mA Class 2 16 — 21 mA Class 3 25 — 31 mA Class 4 35 — 45 mA 7 8.5 10 V — — 9 mA Class 0 and Class 4 PoE 15,400/VOUT 16,170/VOUT 17,600/VOUT mA Class 1 4,000/VOUT 4,200/VOUT 4,600/VOUT mA Class 2 7,000/VOUT 7,350/VOUT 8,000/VOUT mA Class 3 15,400/VOUT 16,170/VOUT 17,600/VOUT mA Class 4 PoE+ 30,000/VOUT 31,500/VOUT 34,200/VOUT mA Mark Voltage VMARK Mark Current IMARK_LIM Short circuit Protection and Current Control Overload Current Threshold2,3 Overload Current Limit4 Overload Time Disconnect Current ICUT ILIM Class 0/1/2/3 and Class 4 PoE; Output = 100 across VOUT 400 425 450 mA ILIM PoE+ Class 4 PoE+; Output = 50 across VOUT 684 750 825 mA TLIM Class 0/1/2/3 and Class 4 PoE; Output = 100 across VOUT 50 60 75 ms Class 4 PoE+; Output = 50 across VOUT 14 17 20 ms Disconnect current 5 7.5 10 mA (PIN @ VIN) to (POUT @ VOUT) — 93 — % IMIN Efficiency System Efficiency Notes: 1. Typical specifications are based on an ambient operating temperature of 25 °C and VIN = +50 V unless otherwise specified. 2. Absolute classification current limits are configurable. See “5.2. Classification” and "5.3. Power-Up" on page 13. 3. Typical ICUT values are adjusted according to the input voltage to provide power limiting with approximately 5% margin against the 802.3 requirements. The maximum ICUT values are consistent with the IEEE requirement that Icut maximum is less than 400 mA at the minimum allowed Vout of 44 V or 684 mA for PoE+ mode at the minimum allowed Vout of 50 V. 4. Overload current is within limits, typically in less than 1 ms. 8 Rev. 1.0 Si3461 2.2. PSE Timing Characteristics When implemented in accordance with the recommended external components and layout guidelines, the Si3461 controller enables the following typical performance characteristics in single-port PSE applications. Refer to the Si3461-EVB applications note, schematics, and user's guide for more details. Table 5. PSE Timing Description Endpoint Detection Delay Cycle Detection Time Symbol Test Conditions Min tDET_CYCLE Time from PD connection to port to completion of detection process. 90 tDETECT Time required to measure PD signature resistance. — Class 0/1/2/3; Time from successful detect mode to classification complete. — Class 4, two event classification; Time from successful detect mode to classification complete. — Class 0/1/2/3 and Class 4 PoE; — 30 — ms Class 4 PoE+ — 69 — ms Class 0/1/2/3 and Class 4 PoE; Time from when a valid detection is completed until VOUT power is applied — Class 4 PoE+; Time from when a valid detection is completed until VOUT power is applied — Classification Delay Cycle tCLASS_CYCLE Classification Time tCLASS Power-Up Turn-On Delay tPWRUP Midspan Detect Backoff Time Error Delay Time Disconnect Delay Ted Time from error to restart of detection in auto-restart mode. Unit 460 ms — 90 — ms — ms — 76 ms — 112 2.0 ms — 99 — tDC_DIS Max 60 2.0 tBOM Typ ms — — — — 350 — s s ms Note: These typical specifications are based on an ambient operating temperature of 25 °C and VIN = +50 V. Rev. 1.0 9 Si3461 3. Typical Si3461-EVB Waveforms Note: Voltages are negative going with respect to the positive input. Powering a PoE+ Device Ch1: PoE output voltage referenced to the +50V rail Powering a PoE Device Detection Time Ch1: PoE output voltage referenced to the +50V rail Ch1: PoE output voltage referenced to the +50V rail Mark Pulse Detection Detection g Two event classification Classification Classification and Power-up Delay PoE+ Ch1: PoE output voltage referenced to the +50V rail TDETECT Power-on Power-on Classification and Power-up Delay PoE Midspan Backoff after bad Classification result Ch1: PoE output voltage referenced to the +50V rail Detection Detection tCLASS_CYCLE tCLASS_CYCLE Classification Classification tPWRUP PoE Current Limit Response Overload During Classification tLIM PoE+ tLIM PoE Figure 2. Typical Si3461-EVB Waveforms 10 Rev. 1.0 ICLASS PoE ILIM ILIM PoE+ PoE+ Current Limit Response tBOM tPWRUP Si3461 4. Si3461-EVB Functional Description In combination with low-cost external components, the Si3461 controller provides a complete PSE solution for embedded PoE applications. The Si3461-EVB reference design operates from a +50 V isolated power supply and delivers power to the powered device through a FET switch without controlling the output voltage while in the power-on state. Refer to the Si3461-EVB User's Guide and schematics for descriptions in the following sections. The basic sequence of applying power is shown in Figure 3. Following is the description of the function that must be performed in each phase. Ch1: PoE output voltage referenced to the +50V rail -2.8V -10V Detection -15.5V -20.5V Classification -44V Power-on -57V tDET_CYCLE tCLASS_CYCLE tPWRUP Figure 3. Basic Power-up Sequence Rev. 1.0 11 Si3461 4.1. Reset State At power-up or if reset is held low, the Si3461 is in an inactive state with the pass FET Q4 off. 4.2. Operating Mode Configuration At power-up, the Si3461 reads the voltage on the STATUS pin, which is set by a DIP switch and a resistor network. The STATUS pin voltage level configures all of the Si3461's operating modes as summarized in Table 6. Table 6. Operating Modes1,2,3,4 STATUS Pin Voltage (V) Operating Mode PSE Type Midspan/ Endpoint Restart Action on Fault or Overload Event Condition Available Power (W) < 0.122 1 Midspan Restart after disconnection 4 0.122 to 0.338 1 Midspan Restart after disconnection 7 0.338 to 0.548 1 Midspan Restart after disconnection 15.4 0.548 to 0.756 2 Midspan Restart after disconnection 30 0.756 to 0.961 1 Midspan Auto restart after 2 s 4 0.961 to 1.162 1 Midspan Auto restart after 2 s 7 1.162 to 1.366 1 Midspan Auto restart after 2 s 15.4 1.366 to 1.575 2 Midspan Auto restart after 2 s 30 1.575 to 1.784 1 Endpoint Restart after disconnection 4 1.784 to 1.990 1 Endpoint Restart after disconnection 7 1.990 to 2.196 1 Endpoint Restart after disconnection 15.4 2.196 to 2.407 2 Endpoint Restart after disconnection 30 2.407 to 2.618 1 Endpoint Auto restart after 2 s 4 2.618 to 2.838 1 Endpoint Auto restart after 2 s 7 2.838 to 3.044 1 Endpoint Auto restart after 2 s 15.4 > 3.044 2 Endpoint Auto restart after 2 s 30 Notes: 1. After power-up, the STATUS pin drives the base of an NPN transistor that controls an LED. 2. There is a trade-off in selecting the mode setting resistor values between voltage step accuracy and additional worstcase supply current. For high-value resistors, the base current will alter the voltage steps while low-value resistors may place higher load on the STATUS pin while driving the LED. The suggested resulting parallel resistance used by the Si3461-EVB is 2.0 k. 3. Each mode setting resistor should be connected either to GND or +3.3 V through the DIP switch. Care should be taken not to short the +3.3 V supply to GND. 4. A reset is required after a DIP switch position change for the new mode to take effect. 12 Rev. 1.0 Si3461 5. Operating Mode Sequencing 5.1. Detection After power-up the Si3461 enters the detection state with the pass FET off. Prior to turning the FET on, a valid detection sequence must take place. According to the IEEE specifications, the detection process consists of sensing a nominal 25 k signature resistance in parallel with up to 0.15 µF of capacitance. To eliminate the possibility of false detection events, the Si3461-EVB reference design performs a robust 3-point detection sequence by varying the voltage across the load that connects to the +50 V supply rail and returns to GND via D3, Q14, R26, and R37. R37 serves as a current sensing resistor, and the Si3461 monitors the voltage drop across it during the detection process. At the beginning of the detection sequence, VOUT is at zero; then, it is varied from 4 to 8 V and then back to 4 V for 20+20+50 ms at each respective level. If the PD's signature resistance is in the RGOOD range of 17 to 29 k, the Si3461 proceeds to classification and power-up. If the PD resistance is not in this range, the detection sequence repeats continuously. Detection is sequenced approximately every 400 ms for endspan and 2.2 seconds for midspan configurations and repeats until RGOOD is sensed, indicating a valid PD has been detected. The STATUS LED (D2) is flashed at a rate of about 1.5 Hz to indicate the PSE is searching for a valid PD. 5.2. Classification After a valid PD is detected, the PSE interrogates the PD to find its power requirement. This procedure is called classification and may be carried out in different ways. The Si3461 implements the one-event classification for Type1 PDs and the two-event classification for Type2 PDs. For one-event classification, the pass FET Q4 is turned on and programmed for an output voltage of 18 V with a current limit of 75 mA for 30 ms. For the two-event classification, the 18 V pulse is output twice with an 8.5 V amplitude mark pulse for 10 ms between the two classification pulses. The current measured at the ISENSE input during the classification process determines the class level of the PD (refer to Table 4 on page 7 for current ranges). If the Si3461-EVB has 30 W of available power, it attempts to classify a Type2 PD first by the two-event method. If the detected class is other than Class 4 or there is less than 30 W of power available, the Si3461 tries to classify a Type1 PD using the one-event method. If the class level of the PD is not within the supported range as set by the initial voltage on the Si3461's STATUS pin (refer to the Operating Mode Configuration section above), an error is declared, and the LED blinks rapidly at a 10 Hz rate. This is referred to as classification-based power denial. If the class level is in the supported range, the Si3461 proceeds to power-up. This is referred to as classification-based power granting. If the classification level is at a greater power than can be supported based on the voltage read by the STATUS pin during start-up, an error condition is reported by flashing the LED at a 10 Hz rate for two seconds before the state machine goes back to the detection cycle. 5.3. Power-Up After successful classification, the pass FET is turned on with an initial current limit of 425 mA (for all PD classes), and the respective ILIM values (indicated in Table 4) take effect after the FET is fully turned on. After power-up is complete, power is applied to VOUT as long as there is not an overcurrent fault, disconnect, or input undervoltage (UVLO) or overvoltage (OVLO) condition. The STATUS LED is continuously lit when power is applied. If the output power exceeds the level of the power requested during classification, the Si3461 will declare an error and shut down the port, flashing the LED rapidly to indicate the error. Depending on the initial voltage on the STATUS pin, the Si3461 will wait either 2.2 seconds or until the PD has been disconnected before it enters the detection phase again to look for a valid load. Rev. 1.0 13 Si3461 5.4. Overload Protection The Si3461 implements a two-level overload protection scheme. The output current is limited to ILIM, and the output is shut down if the current exceeds ICUT for more than 60 ms. If current limitation persists for more than 15 ms in case of PoE+ Class 4 loads, the output is shut down to protect the pass FET. Current limit values are dynamically set according to the power level granted during the classification process and the effective output voltage (refer to Table 4 on page 7 for current limit values). A special 425 mA current limit applies until the FET is fully turned on. If the FET does not fully turn on in the first 75 ms due to an overload condition, an error is declared. The maximum time that the 425 mA inrush current is supplied is about 70 ms due to a 5 ms period to initially ramp the FET gate voltage. The overload protection is implemented using a timer with a timeout set to 60 ms. If the output current exceeds the ICUT threshold, the timer counts up; otherwise, if the output current drops below ICUT, the timer counts down towards zero at 1/16th the rate. If the timer reaches the set timeout, an overcurrent fault is declared; the channel is shut down (by turning off the external pass FET), and the status LED flashes rapidly at a rate of 10 Hz. If the Si3461 was configured in the “automatic restart” mode during start-up, it will automatically resume the detection process after 2.2 seconds. In the “restart after disconnect” mode of operation, the status LED will flash rapidly, and the Si3461 will not resume detection until it senses a resistance higher than 150 k. This condition can normally be achieved by removing the Ethernet cable from the Si3461-EVB's RJ-45 jack labeled “PoE”. Then, the detection process begins; the status LED blinks at a rate of 1.5 Hz, and the Si3461 is allowed to go into classification and power-up mode if a valid PD signature resistance is detected. 5.5. Disconnect The Si3461 implements a robust disconnect algorithm. If the output current level drops below 7.5 mA typical for more than 350 ms, the Si3461 declares a PD disconnect event, and the pass FET is turned off. The Si3461 automatically resumes the detection process after 500 ms. 5.6. UVLO and OVLO The Si3461-EVB reference design is optimized for 50 V nominal input voltages (44 V minimum to 57 V maximum). If the input voltage drops below 42 V, a UVLO condition is declared, which generates the error condition (LED flashing rapidly). An undervoltage event is a fault condition reported through the status LED as a rapid blinking of 10 flashes per second. In the same way, if the input voltage exceeds 60 V, an OVLO condition is declared. In both cases, the output is shut down. The UVLO and OVLO conditions are continuously monitored in all operating states. 5.7. Status LED Function During the normal detection sequence, the STATUS LED flashes at approximately 1.5 times per second as the detection process continues. After successful power up, the LED glows continuously. If there is an error condition (i.e., class level is beyond programmed value or a fault or over current condition has been detected), the LED flashes rapidly at 10 times per second. This occurs for two seconds for normal error delay, and the detection process will automatically start again after 2.2 s unless a “restart after disconnect condition” was set during the initial configuration. Power will not be provided until an open circuit condition is detected. Once the Si3461-EVB detects an open circuit condition, the LED blinks at 1.5 times per second. If the Powered Device (PD) is disconnected so that a disconnect event occurs, the LED will start flashing at 1.5 times per second once the detect process resumes. 14 Rev. 1.0 Si3461 6. Design Considerations 6.1. Isolation The Si3461-EVB's PSE output power at VOUT is not isolated from the input power source (VIN). Isolation of PSE output power requires that the input be isolated from earth ground. Typically, an ac-to-dc power supply is used to provide the 50 V power so the output of this supply is isolated from earth ground. 6.2. External Component Selection Detailed notes on external component selection are provided in the Si3461-EVB User's Guide schematics and BOM. In general, these recommendations must be followed closely to ensure output power stability, surge protection (surge protection diode), and overall IEEE 802.3 compliance. 6.3. Input DC Supply The Si3461-EVB reference design requires an isolated 50 V nominal dc input voltage (with a minimum of 44 V and a maximum of 57 V). The input power supply should be rated for at least 10% higher power level than the output power level chosen. This is primarily to account for the losses in the current-sensing resistor, the pass FET, and the series protection diode of the Si3461-EVB reference design. For example, to support a Class 0 PSE, the input supply should be capable of supplying at least 16.94 W (15.4 W x 1.10 = 16.94 W). The power supply also needs to be able to source 425 mA for 60 ms for normal operation or 885 mA for 15 ms for high power (PoE+) operation. The Si3461-EVB reference design does not regulate the output voltage during the power-on state; therefore, the input dc supply should meet the ripple and noise specifications of the IEEE 802.3 standard. The Si3461-EVB reference design includes an optional 3.3 V shunt regulator that uses the 50 V input to generate the 3.3 V supply voltage for the Si3461 controller. Alternatively, an external 3.3 V power source may be used. Rev. 1.0 15 Si3461 7. Si3461 Pin Descriptions Si3461 pin functionality is described in Table 7. Note that the information applies to the Si3461 device pins, while the Si3461-EVB User's Guide describes the inputs and outputs of the evaluation system. Refer to the complete Si3461-EVB schematics and BOM listing for information about the external components needed for the complete PSE application circuit. 11 11 Si3461 CLSMARK 1 10 STATUS DC1 2 9 ISENSE VDD 3 8 RST DC2 4 7 VSENSE CLSMODE 5 6 DETA 11 11 GND 11-pin QFN (3x3 mm) Top View—Pads on bottom of package Table 7. Si3461 Pin Functionality Pin # Pin Name Pin Type 1 CLSMARK Digital output Logic high on this output increases the current capability of the detection circuitry while used for mark pulse generation. Refer to the Si3461-EVB schematics. 2 DC1 Digital output This is a PWM output providing the dc control voltage for the detection circuitry. It is also combined with the DC2 output in a ratio of 1:256 to provide the gate control voltage of the pass FET. 3 VDD Power 4 DC2 Digital output This is a PWM output that (combined with the DC1 output) provides the gate control voltage of the pass FET with high resolution. 5 CLSMODE Digital output This is an open drain output. When high, it enables the feedback path controlling the 18 V classification voltage. 16 Pin Function 3.3 V power supply input. 6 DETA Analog input DETA is an analog input pin. During the detection process, the DC1 pin duty cycle is varied to generate filtered dc voltages across the load, and the voltage drop across a current sensing resistor is measured through the DETA input. 7 VSENSE Analog input VSENSE is an analog input used for sensing the input dc voltage. 8 RST Digital input Active low reset input. When low, it places the Si3461 device into an inactive state. When pulled high, the device begins the detection process sequence. 9 ISENSE Analog input ISENSE is an analog input connected to a current sense resistor for output current sensing. Rev. 1.0 Si3461 Table 7. Si3461 Pin Functionality (Continued) Pin # Pin Name Pin Type Pin Function At power-up, the voltage on this pin is sensed to configure the PSE available power, mid span/end span timing mode and the device's restart behavior when a fault condition is detected. Refer to "4.2. Operating Mode Configuration" on page 12. After reading the voltage present at this pin at power-up, the STATUS pin becomes a digital output used to control an external LED, which indicates when a detect, power good, or output fault condition has occurred. Logic high turns the LED on, and logic low turns the LED off. Refer to "5.7. Status LED Function" on page 14. 10 STATUS Analog in/Digital out 11 GND GND Ground connection for the Si3461. Rev. 1.0 17 Si3461 8. Ordering Guide Ordering Part Number Description Package Information Temperature Range (Ambient) Si3461-E02-GM Single-port PSE controller 11-pin, 3 x 3 mm QFN. RoHS compliant –40 to 85 °C Si3461-KIT Si3461 evaluation board and reference design kit Evaluation board N/A Notes: 1. Add R to part number to denote tape-and-reel option (e.g., Si3461-E02-GMR). 2. The ordering part number above is not the same as the device mark. See "9.3. Marking Specification" on page 22 for more information. 18 Rev. 1.0 Si3461 9. Package Outline: 11-Pin QFN Figure 4 illustrates the package details for the Si3461. Table 8 lists the values for the dimensions shown in the illustration. The Si3461 is packaged in an industry-standard, 3x3 mm, RoHS-compliant, 11-pin QFN package. Figure 4. QFN-11 Package Drawing Table 8. Package Diagram Dimensions Dimension Min Nom Max A 0.80 0.90 1.00 A1 0.03 0.07 0.11 A3 b 0.25 REF 0.18 0.25 D D2 0.30 3.00 BSC. 1.30 1.35 e 0.50 BSC. E 3.00 BSC. 1.40 E2 2.20 2.25 2.30 L .45 .55 .65 aaa — — 0.15 bbb — — 0.15 ddd — — 0.05 eee — — 0.08 Notes: 1. All dimensions shown are in millimeters (mm) unless otherwise noted. 2. Dimensioning and Tolerancing per ANSI Y14.5M-1994. 3. This drawing conforms to JEDEC outline MO-243, variation VEED except for custom features D2, E2, and L which are toleranced per supplier designation. 4. Recommended card reflow profile is per the JEDEC/IPC J-STD-020C specification for Small Body Components. Rev. 1.0 19 Si3461 9.1. Solder Paste Mask 0.10 mm b 0.10 mm LT 0.50 mm D4 0.35 mm 0.50 mm 0.30 mm 0.35 mm 0.20 mm L 0.30 mm D b D2 0.20 mm E2 0.70 mm e 0.60 mm 0.20 mm 0.30 mm e E Figure 5. Solder Paste Mask 20 Rev. 1.0 D4 LB k Si3461 9.2. PCB Landing Pattern 0.10 mm b 0.10 mm 0.35 mm D4 LT 0.50 mm 0.30 mm D D2 L b 0.20 mm e E2 0.20 mm 0.30 mm D4 LB k 0.10 mm e E Figure 6. Typical QFN-11 Landing Diagram Rev. 1.0 21 Si3461 9.3. Marking Specification The top of the Si3461 package is marked as shown in Figure 7. 6102 ETTT YWW+ Figure 7. QFN 11 Top Marking Table 9. Top Marking Explanation Line 1 Marking: Pin 1 Identifier Circle = 0.25 mm Diameter Product ID 6102 61 = Si3461; 02 = Firmware Revision 02 Line 2 Marking: ETTT = Trace Code Assembly trace code E = Product revision TTT = Assembly trace code Line 3 Marking: YWW = Date Code Assigned by the Assembly contractor. Y = Last Digit of Current Year (ex: 2009 = 9) WW = Current Work Week Lead-Free Designator + 22 Rev. 1.0 Si3461 DOCUMENT CHANGE LIST Revision 0.1 to Revision 0.2 Updated "9.3. Marking Specification" on page 22. Revision 0.2 to Revision 0.3 Updated "8. Ordering Guide" on page 18. Revision 0.3 to Revision 1.0 Updated firmware revision to 02. Updated Table 3 on page 6 Made consistent with firmware revision 02. previous errors for IOH and VIL values. Corrected Updated Table 4 on page 7 Added min OVLO and max UVLO limits. IIN so as not to include the shunt regulator current. Updated ICUT values to be consistent with IEEE specification. Updated Updated Table 6 on page 12. Update suggested parallel resistance at status pin in Note 2. Rev. 1.0 23 Si3461 CONTACT INFORMATION Silicon Laboratories Inc. 400 West Cesar Chavez Austin, TX 78701 Tel: 1+(512) 416-8500 Fax: 1+(512) 416-9669 Toll Free: 1+(877) 444-3032 Please visit the Silicon Labs Technical Support web page: https://www.silabs.com/support/pages/contacttechnicalsupport.aspx and register to submit a technical support request. The information in this document is believed to be accurate in all respects at the time of publication but is subject to change without notice. Silicon Laboratories assumes no responsibility for errors and omissions, and disclaims responsibility for any consequences resulting from the use of information included herein. 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